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Published byAlice Sylvia Terry Modified over 9 years ago
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AQUA AURA The Berkeley High Spatial Resolution(BEHR) OMI NO2 Retrieval: Recent Trends in NO2 Ronald C. Cohen University of California, Berkeley $$ NASA
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Air Quality Applications Of OMI NO2
Key elements: total columns trends over time differences and ratios in space the noontime chemical lifetime of NO2 of ~1-4hrs implies an e-folding distance of order 25km OH changes will be approximately equal to NO2 changes—a significant effect on lifetimes
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L Valin et al., Atmos. Chem. Phys. 2011
Four Corners Power Plants: WRF-Chem L Valin et al., Atmos. Chem. Phys. 2011
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Los Angeles: WRF-Chem
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OMI NO2 Riyadh 8 hours 6 hours
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Deriving NO2 column densities from space-based reflectance measurements
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Summary of the NO2 retrieval process
Step 1: DOAS fit to determine slant column Step 2: Subtract the Stratospheric contribution Step 3: Convert the tropospheric slant column into a vertical column Total Slant Column Density Stratospheric Vertical Column Density Tropospheric Vertical Column Density
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Step 3: Convert the tropospheric slant column into a vertical column
Atmosphere Absorption and Scattering by aerosols and molecules Absorption, Scattering, and Transmission through a cloud Absorption and Scattering by the surface Modified image from Richter, U Bremen Surface AMFs are sensitive to Viewing geometry Terrain pressure and reflectivity Shape (not magnitude) of the NO2 vertical profile Clouds AMF = Vertical Column Slant Column
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Berkeley High Resolution Retrieval (BEHR)
NASA standard BEHR Terrain pressure High-res terrain database, center of OMI footprint High-res terrain database, average over OMI footprint Terrain reflectivity Monthly 1° × 1° MODIS, 8 day 0.05° × 0.05° NO2 profile shape Annually 2° × 2.5° WRF-Chem, Monthly 4 × 4 km2 (CA&NV) 12 x 12 km2 U.S. Clouds OMI cloud product MODIS cloud product Russell et al., Atmos Chem & Phys 11, , 2011
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NASA Standard Product June 2008
Terrain Reflectivity (Albedo) MODIS True Color OMI Monthly Albedo MODIS 8 day Albedo SP NO June 18, 2008 NASA Standard Product June 2008 BEHR June 2008 Russell et al., Atmos Chem & Phys, 2011
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Terrain Reflectivity (Albedo)
PDF of systematic errors Russell et al., Atmos Chem & Phys, 2011
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Terrain Pressure PDF of systematic errors
Russell et al., Atmos Chem & Phys, 2011
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NO2 profile shape PDF of systematic errors
Russell et al., Atmos Chem & Phys, 2011
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The BEHR product is generally higher in urban regions and lower in rural regions than the operational products Standard Product BEHR % Difference Russell et al., Atmos Chem & Phys, 2011
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molecules cm-2 Summer 2005 Russell et al., ACPD in press
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molecules cm-2 Summer 2011 Russell et al., in press
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Trends for select cities and power plants
–– Weekdays - - Weekends –– All days Russell et al., in press
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Trends in cities are similar while trends at power plants are more variable
47 cities, 23 power plants! Russell et al., in press
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2005 – 2011 reductions in urban regions of the US are similar (–32 ± 7%).
Russell et al., in press
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The impact of the economic recession on emissions is observed by OMI
2005 – 2007 Russell et al., in press
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The impact of the economic recession on emissions is observed by OMI
2005 – 2007 2007 – 2009 Russell et al., in preparation
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The impact of the economic recession on emissions is observed by OMI
2005 – 2007 2007 – 2009 2009 – 2011 2005 – 2007 Russell et al., in press
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Reductions on weekdays are larger than those on weekends due to reductions in diesel traffic
2005 – – – 2011 Weekday – 6 ± 4% – 9 ± 4% – 4 ± 4% Weekend – 7 ± 5% – 6 ± 7% – 1 ± 7% Russell et al., in press
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Conclusions The BEHR product reduces biases in the NO2 column due to coarse resolution terrain and profile parameters. We can make it available upon request, Analysis of 2005–2011 trends for cities and power plants in the US show how improved vehicle technology and the economic downturn have influenced emissions.
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Ashley Russell Luke Valin (PhD May 2012) (PhD soon)
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A.R. Russell, et al, Trends in OMI NO2 observations over the United States: Effects of emission control technology and the economic recession, ACPD. in press June 2012. L.C. Valin, et al, Effects of model resolution on the interpretation of satellite NO2 observations, ACP. 11, , 2011 A.R. Russell, et al., A high spatial resolution retrieval of NO2 column densities from OMI: Method and Evaluation, ACP, 11, , 2011. L.C. Valin, et al., Observation of slant column NO2 using the super-zoom mode of AURA OMI, AMT, 4, , 2011. A.K. Mebust,, Characterization of wildfire NOx emissions using MODIS fire radiative power and OMI tropospheric NO2 columns , ACP. 11, , 2011. R.C. Hudman, et al., Interannual variation in soil NOx emissions observed from Space, ACP. 10, , 2010. Thank you!
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Update: Trends in urban regions of CA, 2005-2011
- 36% - 30% - 44% - 30% Russell et al., 2010 (updated)
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I = Io e - σ ℓ N Beer-Lambert Law: Entangled ℓ CLOUDS SAMPLE POLISHED
MIRROR LIGHT SOURCE (Io) ℓ MOLECULES PARTICLES Beer-Lambert Law: I = Io e - σ ℓ N DETECTOR (I) Entangled 28
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WRF-CHEM 1km – 4-Corners Plume
NO2 column OH Column
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Large Area+Urban Sources in WRF-Chem
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NOx Lifetime τ=Mobs / Erate e-kx; x = ut; τ=k-1 By Mass
Integrated Observation By Decay Gradient e-kx; x = ut; τ=k-1 Resolved Observation
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